I agree with thalib. Say you can take the mugger ( bad assumption) but for the sake of whatever there is a sake for! (hu?) anyways its like give a man a fish feed him for a day, teach a man how to fish feed him for life. So, you give the scum your wallet, whats he learn? That he can make money by threatning people with a weapon. But, if you take him and retain him he might have second thoughts. Runnings great but as Marc "Animal" Young likes to point out just taking tail and running wont work 90% of the time. Your assuming a few things. heres a few to name:

1. you faster than your enemy.
2. you know your way out and around faster ( how do you know he doesn't have any friends hiding?
3. he's alone.

and more. As for the 6 year old metiphore I dissagree that taking Aikido would be the best thing for training in something like that. Teachers all over the world handle that same situation without any Aikido training whatsoever better most aikidokas can!